Text Formatting ⇒ CALCULATOR PACKAGE, CHECK A NUMBER

[phanttam]

I have a problem about CALCULATOR PACKAGE, I need check #1 is a number or not, could I use contitional command?
ex:
def \CHECK#1{
% if #1 a number
\if...?
#1 is a number
\else
#1 is not a number
\fi
}
\CHECK{3}

CHECK{n}

Thanks all!

[Stefan Kottwitz]

Welcome to the forum!

What do you mean by "CALCULATOR PACKAGE"? What is this?

And what exactly do yo try to achieve? Maybe we can help doing it using another package as well.

Stefan

[phanttam]

Thanks Stefan_K, could you introduce me another package?
I need if #1 = n
\sum\limits_{k=0}^{n}2^k=1+2+2^2+\ldots+2^{n-1}+2^n
else
\sum\limits_{k=0}^{2016}2^k=1+2+2^2+\ldots+2^{2015}+2^2016

I can

Code: Select all

\def \SUM#1{
% check #1 is a number or not, if #1 is a number
$\sum\limits_{k=0}^{#1}2^k=1+2+2^2+\ldots+2^{\SUBTRACT{#1}{1}{\sol}\sol}+2^{#1}$
\else
$\sum\limits_{k=0}^{n}2^k=1+2+2^2+\ldots+2^{n-1}+2^n$
\fi
}
\SUM{n}

\SUM{2016}

[Johannes_B]

Code: Select all

\def \SUM#1{
	$$\sum\limits_{k=0}^{#1}2^k=1+2+2^2+\ldots+2^{#1-1}+2^{#1}$$
}
\SUM{n}

\SUM{2016}
\vfill
\eject
\bye